As for microcomputers, there is an incessant request for reduction in a chip size. A largest possible decrease in the number of external terminal is therefore an assignment to be achieved. For example, according to a technology disclosed in patent document 1 (JP-A-2001-273247), when an operating mode is externally designated for a microcomputer that operates with multiple operating modes switched, the operating mode is designated based on the level of a signal to be applied to a forcible reset terminal at the timing at which power-on reset is canceled. In this configuration, the necessity of a terminal to be used exclusively to designate an operating mode is obviated.
However, the technology disclosed in the patent document 1 has underlying problems described below.
(1) If noise is convoluted to a reset terminal at the timing at which power-on reset is canceled, there is a fear that an incorrect operating mode may be selected.
(2) If latched data holding an operating mode is affected by, for example, alpha rays or electromagnetic noise, an incorrect operating mode is kept held.
(3) Only two operating modes can be designated.
Thus, it is required to provide a microcomputer capable of being set to a larger number of operating modes with the number of operating mode designation terminals minimized, and a functional evaluation chip that includes the microcomputer and is employed in a development stage.